The present invention relates to a locking/unlocking device for a knee prosthesis, operating by means of the wearer's energy alone, usable especially in cases of femoral amputation.
There are many sophisticated devices using hydraulic cylinder systems with solenoid valves driven from information given by sensors, incorporating microprocessors. Due to the presence of systems using electrical means, it is necessary to provide a source of electrical energy and a means of recharging the source.
These sophisticated devices make it possible to make very accurate adjustments but they have many drawbacks; in particular, they are complex and costly or even very costly.
In countries that have a well-developed medical infrastructure, amputations are performed, particularly, as a result of accidents or chronic vascular disease associated with diabetes, and on some people with low muscular potential who are seeking means of walking more safely.
In countries with limited medical infrastructure, access to sophisticated prostheses is even more difficult.
French patent FR 2 972 920 discloses a control device for a knee prosthesis for a leg.
This control device is fully mechanical and very compact. It requires only low maintenance and is more affordable.
Such a control device is suitable for applications in large numbers, particularly intended for children.
To achieve this goal there are two articulated sections that rotate in relation to each other. One of these is the femoral section secured to the amputated part of the femur via any suitable means, and the other is the tibial section which receives an artificial shin and foot in a manner known per se.
The purpose of this prosthesis of the prior art is to ensure at least one freedom of the rotating joint when the wearer raises his/her leg and when the latter is not supported on the ground, and blocks rotation when the leg is supported on the ground, to allow the body to tilt forward, generating as natural a walking movement as possible for the wearer.
This prosthesis of the prior art proposes a solution incorporating a freewheel and means of controlling the freewheel. These control means are controlled by a cable mounted on two pulleys with a pretensioning spring and a movable plate which stretches or relaxes the cable making it possible to block or release the freewheel.
Mounting these cable control means is a tricky operation requiring an adjusted cable, and a cable pretensioning spring or similar means.